Communicating over multiple radio access technologies (RATs)

ABSTRACT

Downlink control plane information may be transmitted with a first radio access technology (RAT) of a first frequency. Downlink user plane data may be transmitted with utilization of a second RAT of a second frequency. The downlink user plane data may be multicast multimedia data and communicated based on the downlink control plane information. The first RAT and the second RAT may communicate with a same gateway to allow a direct tunnel transmission from a broadcast or multicast service center to a user equipment (UE).

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/016,559, filed Sep. 3, 2013, which is a continuation of U.S. patentapplication Ser. No. 11/502,929, filed Aug. 11, 2006, which issued asU.S. Pat. No. 8,532,653 on Sep. 10, 2013, which is incorporated byreference as if fully set forth.

BACKGROUND OF INVENTION

Mobile operators worldwide have launched streaming real-time services(such as mobile TV and radio) over their existing 3G Universal Mobiletelecommunications System (UMTS) networks. However, the existing UMTSair-interface and overall network architecture are not adequate todeliver high quality, bandwidth-demanding multimedia content, such astelevision for a large number of users. Consequently, the 3GPP standardsconsortium identifies optimizations in the UTRAN and the core networksystem architecture that will allow the deployment of broadcasting-typeapplications over a UMTS air-interface and core network.

The add-on framework to the UMTS system architecture in a family of 3GPPspecifications is called Multimedia Multicasting/Broadcasting Service(MBMS). The MBMS framework identifies the modifications needed in theUMTS Radio Access Network (RAN) and describes service aspects, such assecurity and charging in a set of 3GPP specifications (see, for example,references [1], [2], [4], [8]). 3GPP2 has defined a similar service in afamily of specifications called Broadcast Multicast Service (BCMCS).

MBMS/BCMCS represents a point-to-multipoint service architecture definedin an end-to-end manner within the family of 3GPP/2 specifications thatallow a 3G operator to deploy a broadcasting/multicasting service. Forexample, Mobile TV is deployed over its allocated spectrum by upgradingthe existing network with the relevant 3GPP2 MBMS/BCMCS specifications.

MBMS/BCMCS multimedia streaming traffic and the associateduplink/downlink signaling are conventionally transmitted from the samenetwork on the same frequency band. Because MBMS is intended to serve alarge user population, the high volume of broadcast/multicast trafficand the number of processing nodes along its path impose a significantperformance strain on the existing core network and UTRA elements of theUMTS network. For example, the core network mobility anchor (e.g., SGSNin 3GPP UMTS), and the radio network controller (e.g., RNC in 3GPP UMTS)must process and transport the “normal” point-to-point traffic generatedby the different packet and circuit-switched applications. Therefore, away to reduce the strain on the network is desired.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the invention provide methods and apparatus to alleviatepotential capacity problems in the radio access and core networksoperating MBMS by separating the control and user plane of the MBMStraffic (a “one tunnel” approach) across two different Radio AccessTechnologies (RAT) of the 3GPP family of RATs, and their equivalent CoreNetwork transport path.

Overload traffic conditions for multimedia services may be reduced bytransmitting the traffic related to broadcasting multimedia over a firstwireless network (defined by one RAT), and the associated controlinformation over a second wireless network (defined by a substantiallydifferent RAT). The two networks may operate on substantially differentfrequency bands. Thus, the wireless terminal may receive a plurality ofsignals originating from a plurality networks.

A mobile operator may have both a paired and an unpaired spectrum. Inthe unpaired spectrum, the mobile radio technology may use Time DivisionDuplexing (TDD). In the paired spectrum, the mobile radio technology mayuse Frequency Division Duplexing (FDD). The multicast traffic is highlyasymmetric. Thus, the multicast traffic is adequately matched to theunpaired spectrum, in which the ratio of downlink to uplink traffic maybe adjusted to reflect the traffic demand. Moreover, the ratio may beadjusted such that the entire unpaired spectrum is dedicated todownlink. In this way, maximum utilization of the available spectrum isachieved. Under this scenario, the return channel is no longer presentin the unpaired spectrum, and the user relies on the paired spectrum toprovide the return channel.

More particularly, embodiments of the invention separate the paths ofthe multicasting/broadcasting traffic across multiple access and corenetworks into Control Plane (CP) and User Plane (UP)multicasting/broadcasting traffic. UP multicasting/broadcasting trafficis the actual multimedia content delivered in the downlink. CP is thesupplemental traffic that is associated with the UPmulticasting/broadcasting traffic. Both the UP and CP are relevant tonetwork-specific signaling procedures and “higher-layer”application-related signaling that applies to themulticasting/broadcasting user service.

The coupling between a first network and a second network by a homegateway allows for a direct tunnel transmission from abroadcast/multicast service center to a user equipment. User equipment(UE) may transmit control uplink signals via the first network.Simultaneously, the UE receives downlink control signals via the firstnetwork. The broadcast multimedia service is received at the userequipment via a second network in response to the exchange of uplink anddownlink signals between the user equipment and the first networkthrough the home gateway.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary embodiment of logical architecture of anetwork with Multimedia Multicasting/Broadcasting Service (MBMS)capabilities.

FIG. 2 illustrates an exemplary embodiment of the signaling flow toestablish a direct user plane tunnel for the delivery of multicastingtraffic.

FIG. 3 illustrates an exemplary embodiment of a UMTS network withMultimedia Multicasting/Broadcasting Service (MBMS) capabilities.

FIG. 4 illustrates an exemplary embodiment of the signaling flow forMBMS multicast delivery mode signaling procedures, using “one tunnel”approach and downlink-only TD-CDMA radio interface.

FIG. 5 illustrates an exemplary embodiment of the detailed stepsinvolved in MBMS context provisioning in RAN with direct user plane.

FIG. 6 illustrates an exemplary embodiment of a computing system capableof carrying out the functionality of the various embodiments.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an exemplary embodiment of the logical architectureof a network with a point-to-multipoint service center (e.g., an MBMSservice center). A first network is defined by RAT1, and a secondnetwork is defined by RAT2. Each RAT is implemented by a radiocontroller (e.g., RAT1 radio controller 106 and RAT2 radio controller108). The radio controller (RC) is the control element in the radioaccess network (RAN) responsible for controlling the base stations 104of a specific RAT. The RC carries out radio resource and mobilitymanagement functions. This is the point in the network where encryptionmay be done before user data is sent to and from the mobile UE 102.

The UE 102 communicates with RAT1 and RAT2 via base stations 104 coupledto the RAT1 RC 106 and RAT2 RC 108. The UE wireless terminal 102includes a first receiver, a second receiver, and a transmitter. The UE102 may receive signals simultaneously from RAT1 and from RAT2. In otherwords, the first receiver may receive signals over two differentnetworks, which may operate in different frequency bands.

The mobility anchor 110 is the gateway between the RAN and the corenetwork. Mobility anchoring is performed when the UE 102 is movingacross a RC of the same or different RATs.

The home gateway 112 is a router that serves as a gateway between mobilenetworks and packet data networks. It is the ingress/egress point forthe data traffic entering/exiting the mobile core network, respectively.For the case of MBMS, the home gateway 112 terminates the IP multicastrequest and controls the flow of the IP multicast traffic in the corenetwork.

The UE 102 uses RAT1 to transport the necessary control plane (CP) data.The CP data includes radio and core network signaling data, serviceregistration data, and security-related signaling that is used todeliver the necessary decryption keys from the Broadcasting/MulticastingService Center (BM-SC) 114 to the UE 102.

The BM-SC 114 is the network entity that manages the functions ofsubscription management, user authentication, key distribution, andmultimedia content delivery. The BM-SC 114 provides functions forbroadcasting user service provisioning and delivery. It serves as anentry point for broadcasting traffic transmissions, and authorizes andinitiates the establishment of broadcasting traffic transport bearers.It also distributes the service announcements that schedule the deliveryof a broadcasting service.

The home gateway 112 directly transmits the broadcasting/multicastinguser plane (UP) traffic to the RAT2 RC 108 via controlling nodes,thereby bypassing the mobility anchor 110.

This approach removes the signaling and processing load from the nodesinvolved in the delivery of broadcast multimedia traffic, and leaves thecapacity of the most widely deployed RAT (in this example, RAT1)unaffected.

UE mobility between the two RATs is supported over an interface 116between the RAT1 RC 106 and RAT2 RC 108. The coverage of RAT1 may belarger than that of RAT2. Thus, when UE 102 is no longer in the coveragearea of RAT2, a request to handover the multimedia transmission is madeto RAT1 using messages communicated between the UE 102 and RAT1 RC 106and RAT2 RC 108. The handover messages are similar to well-knownconventional handover messages [14], but contain modified handoverparameters. The UE 102 informs the RAT1 RC 106 that there is a loss ofservice over RAT2. The message may include additional parameters such asa cause value indicating that the handover is initiated due to the lossof MBMS reception over RAT2, and the MBMS service ID (or MBMS serviceIDs if more than one service is activated). The RAT1 RC 106 communicateswith RAT2 RC 108 (over an interface between the two RCs 116) to acquirethe service context for the particular service that the UE 102 hasactivated. After establishing the service context at RAT1 RC 106, theRAT1 RC 106 sends the radio channel setup information to the UE 102 inorder to enable the delivery of the service over RAT1.

FIG. 2 illustrates an exemplary embodiment of signaling flow betweenelements in a mobile network to direct a user plane tunnel for thedelivery of multicasting traffic. The following process follows theestablishment of a point-to-point packet pipe by the UE 102. Themessages between elements in steps 1-4 are “application layer” signalingmessages.

In step 1, the UE 102 receives the service announcement messagetransmitted by the BM-SC 114. The service announcement message indicatesthe details of the broadcasting/multicasting service.

In step 2, the UE 102 communicates signaling messages with the BM-SC 114over a first wireless network, RAT1, to perform the service registrationrequest.

In step 3, the UE 102 communicates with the BM-SC 114 via signalingmessages to request and receive the necessary security keys via RAT1.The security keys are needed to decrypt the received content.

In step 4, the UE 102 communicates signaling messages to join themulticasting service. The messages are intercepted by the home gateway(HGW) 112.

In step 5, the home gateway 112 requests and receives authorization fromthe BM-SC 114 for the UE 102 to allow access to the multicastingservice.

In step 6, after the accepted authorization is received from the BM-SC114 at the home gateway 112, the home gateway 112 proceeds to receiveand establish a point-to multipoint program called a point-to-multipointpacket pipe 202 over RAT2.

In step 7, after the point-to-multipoint pipe 202 is established in step6, the home gateway 112 updates the termination point of thepoint-to-multipoint pipe 202 in order to bypass the RAT1 Mobility Anchor(MA) 110 from the path of the user plane traffic. Thepoint-to-multipoint service, called the point-to-multipoint packet pipe202, transports the multicasting multimedia traffic via the secondnetwork, and terminates at the RAT2 RC 108.

After the establishment of the point-to-multipoint packet pipe 202 overRAT2, the multicasting multimedia traffic is directly transmitted fromthe home gateway 112 to the RAT2 RC 108. From the RAT2 RC 108, themulticasting multimedia traffic is transmitted to the UE 102.

The above embodiments can be implemented in the Rel.6 3GPP networkarchitecture with some enhancements. For example, using two differentRATs, W-CDMA radio network controllers may be used to transport the MBMSsignaling information. W-CDMA is FDD-based. At the same time, TD-CDMARNCs may be used in the downlink-only mode to transport the MBMSmultimedia traffic. TD-CDMA is TDD-based. In another embodiment, the twoRATs may be W-CDMA RNCs. In another embodiment, the two RATs may beTD-CDMA RNCs.

FIG. 3 illustrates an embodiment using UMTS technology. The UE 302communicates with a W-CDMA radio network controller (RNC) 306, whichdefines a first network, and a TD-CDMA RNC 308, which defines a secondnetwork, via node Bs 304. The first network communicates uplink anddownlink control signals to the UE 302. The second network transmits apoint-to-multipoint signal to the UE 302 in response to the uplink anddownlink control signals between the first network and the UE 302. (NodeB 304 is the base station for the UMTS cellular system.)

The mobility anchor for the UMTS core network (W-CDMA) is the SGSN 310.The interface, Iu-PS 320, links the W-CDMA RNC 306 with an SGSN 310.

The home gateway for the UMTS core network is the GGSN 312. The GGSN 312couples the point-to-multipoint service center, the BM-SC 314, with thefirst and second wireless networks.

The interface, Gn, links the SGSN 310 and GGSN 312 core network nodes.The Gn is separated into Gn-C 324 and Gn-U 326: Gn-C 324 indicates thetransport of the control plane messages, such as those referring to theuser plane tunnel establishment and mobility messages; and Gn-U 326indicates the user plane traffic transport. The Gn interface (Gn-C 324and Gn-U 326), in prior art, connect the same nodes (e.g., same RNC andSGSN). In the embodiments of the invention, however, the Gn-C 324terminates in the W-CDMA RNC 306, compared to the Gn-U 326, whichterminates in the TD-CDMA RNC 308.

Two interfaces exist between the GGSN 312 and the BM-SC 314. The Gmb 328is a MBMS-specific interface. It is used for signaling message exchangesbetween GGSN 312 and BM-SC 314. A signaling message exchange may includeuser-specific signaling (such as user-specific charging messages) andMBMS-specific signaling messages (such as the GGSN registration in aBM-SC). The Gi interface 330 is located between the GGSN 312 and theexternal public packet data network. In the embodiments of theinvention, Gi 330 connects the BM-SC 314 and the GGSN 312. Gi 330transports the UP multimedia traffic to the GGSN 312 designated toreceive the MBMS user service.

The Iur 316 interface is located between two RNCs. In an exemplaryembodiment, the Iur 316 may connect two RNCs of the same RAT (e.g.,W-CDMA or TD-CDMA). In other embodiments of the invention, the Iur 316may connect two RNCs of different RATS, for example, a W-CDMA RNC and aTD-CDMA RNC. The Iur interface 316 may transfer a downlink channel setuprequest from the first RNC to a second RNC, and a downlink channelacknowledgment from the second RNC to the first RNC. An embodiment of aspecific signaling exchange between the RNCs is shown in the signalingflow of FIG. 4 and FIG. 5.

If the MBMS service embodiment uses the broadcast delivery mode asdefined in [1], the UE 302 uses the W-CDMA RNC 306 to perform serviceregistration, authenticate with the BM-SC 314, obtain the necessaryencryption keys as defined in [4], and receive the service announcement.Next, the UE 302 performs the necessary procedures to “tune in” to theappropriate MBMS traffic channel (MTCH) transmitted over the UMTSTD-CDMA air-interface in order to receive the MBMS multimedia trafficand then use the previously received keys to decrypt the traffic.

However, if the particular service uses the multicast delivery mode,then the UE may perform multicast delivery mode signaling procedures,described in [1], [4], and [5] with modifications explained in thedetailed description of FIG. 4.

FIG. 4 illustrates an example of a signaling message flow that isimplemented when the MBMS multicast delivery mode signaling proceduresuses a “one tunnel” approach and a downlink-only TD-CDMA radiointerface.

In steps 1-4, the current MBMS signaling procedures apply as describedin the relevant 3GPP specifications [1], using the messages defined in[4] and [2], utilizing the default packet data protocol (PDP) contextover W-CDMA bearers.

In step 1, the service announcement messages communicated between the UE302 and BM-SC 314 indicate that the transport of the MBMS traffic willtake place over the TD-CDMA network.

In step 2, the service registration request messages are communicatedbetween the BM-SC 314 and the UE 302.

Step 3 communicates the modulation request messages between the UE 302and the BM-SC 314.

In step 4, the UE 302 communicates messages to the BM-SC 314 indicatingthat it wants to receive messages addressed to a specific multicastgroup.

For steps 5-9, the current MBMS signaling procedures apply as describedin the relevant 3GPP specifications [1], using the messages defined in[9], [10], and [11].

In steps 5-6, signaling messages between the BM-SC 314 and the GGSN 312consist of a service authorization request from the GGSN 312 and aservice authorization answer from the BM-SC 314 (AA request/answer).

In step 7, after receiving an authorization answer, the GGSN 312 sends aMBMS notification request message to the SGSN 310. In step 8, the SGSN310 then communicates a “Request MBMS Context Activation” message to theUE 302. In step 9, the UE 302 communicates an “Activate MBMS ContextRequest” to the SGSN 310.

The “one tunnel approach” described in [12] and [13] indicates thereserved “not allocated” value for the traffic path as the Iu bearer isnot yet allocated in the RAN.

In step 10, the message “Create MBMS Context Request” is sent from theSGSN 310 to the GGSN 312.

For steps 11-13, the current MBMS signaling procedures apply asdescribed in the relevant 3GPP specifications [1], using the messagesdefined in [9] and [10].

In steps 11-12, signaling messages between the BM-SC 314 and the GGSN312 includes a service authorization request from the GGSN 312, and aservice authorization answer from the BM-SC 314 (AA request/answer).

In step 13, a “Create MBMS context response” message is sent from theGGSN 312 to the SGSN 310.

In step 14, the SGSN 310 allocates the appropriate resources in the RANfor the MBMS context by exchanging signaling information with the W-CDMARNC 306 and the TD-CDMA RNC 308, separating the CP and UP paths over theIu-PS interface 320 and the Iur interface 316 by a downlink channelsetup request.

FIG. 5 illustrates in more detail the MBMS context provisioning in theRadio Access Network (RAN), shown in step 14 of FIG. 4.

In step 14 a, the Radio Access Bearer (RAB) path setup request is sentto the W-CDMA RNC 306 from the SGSN 310. This request includes a TunnelEndpoint ID (TEID) of the GGSN 312 and the address of the GGSN 312.

In step 14 b, the W-CDMA RNC 306 communicates the TEID and the addressof the GGSN 312 to the corresponding TD-CDMA RNC 308 over an “Iur-like”interface. Also, the TD-CDMA RNC 308 is requested for RAB establishmentover the TD-CDMA network by a “Radio Access Bearer Path Setup request”.

In step 14 c the TD-CDMA RNC 308 reserves the resources for RABestablishment and communicates to the W-CDMA RNC 306 indicating a TunnelEndpoint ID (TEID) at the TD-CDMA RNC 308 for the RAB and the address ofthe TD-CDMA RNC 308 in a “Radio Access Bearer Path Setup response”message.

In step 14 d, the information on TEID at TD-CDMA RNC 308 and the addressof the TD-CDMA RNC 308 is delivered to the SGSN 310 from the W-CDMA RNC306 by a “Radio Access Bearer Path Setup response” message.

In step 15, the current MBMS signaling procedures apply as described inthe relevant 3GPP specification [1], using the messages defined in [9],[10], and [11]. The SGSN 310 communicates an “Update MBMS Context”signaling message to the GGSN 312.

In step 16, after the MBMS Context is provisioned in the RAN, the SGSN310 receives an “Update MBMS Context Accept” signaling message from theGGSN 312 and updates the MBMS context indicating the RAN address and theTEID of the TD-CDMA RNC 308 to the GGSN 312.

The GGSN 312 updates the MBMS Context and returns the “Update MBMSContext Response” message. In step 17, the tunnel between the GGSN 312and the TD-CDMA RNC 308 is established.

In embodiments of the invention, the GGSN 312 sends the MBMS user planetraffic directly to the TD-CDMA RNC 308 following the “one tunnel”approach defined in 3GPP. In this embodiment, the method indicates theMBMS transport mechanism using an element in the MBMS serviceannouncement format.

While the invention has been described in terms of particularembodiments and illustrative figures, those of ordinary skill in the artwill recognize that the invention is not limited to the embodiments orfigures described. Although embodiments of the present invention aredescribed, in some instances, using UMTS terminology, those skilled inthe art will recognize that such terms are also used in a generic senseherein, and that the present invention is not limited to such systems.

Those skilled in the art will recognize that the operations of thevarious embodiments may be implemented using hardware, software,firmware, or combinations thereof, as appropriate. For example, someprocesses can be carried out using processors or other digital circuitryunder the control of software, firmware, or hard-wired logic. (The term“logic” herein refers to fixed hardware, programmable logic and/or anappropriate combination thereof, as would be recognized by one skilledin the art to carry out the recited functions.) Software and firmwarecan be stored on computer-readable media. Some other processes can beimplemented using analog circuitry, as is well known to one of ordinaryskill in the art. Additionally, memory or other storage, as well ascommunication components, may be employed in embodiments of theinvention.

FIG. 6 illustrates a typical computing system 600 that may be employedto implement processing functionality in embodiments of the invention.Computing systems of this type may be used in the BM-SC, the radiocontrollers, the base stations and the UEs, for example. Those skilledin the relevant art will also recognize how to implement the inventionusing other computer systems or architectures. Computing system 600 mayrepresent, for example, a desktop, laptop or notebook computer,hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe,server, client, or any other type of special or general purposecomputing device as may be desirable or appropriate for a givenapplication or environment. Computing system 600 can include one or moreprocessors, such as a processor 604. Processor 604 can be implementedusing a general or special purpose processing engine such as, forexample, a microprocessor, microcontroller or other control logic. Inthis example, processor 604 is connected to a bus 602 or othercommunication medium.

Computing system 600 can also include a main memory 608, such as randomaccess memory (RAM) or other dynamic memory, for storing information andinstructions to be executed by processor 604. Main memory 608 also maybe used for storing temporary variables or other intermediateinformation during execution of instructions to be executed by processor604. Computing system 600 may likewise include a read only memory(“ROM”) or other static storage device coupled to bus 602 for storingstatic information and instructions for processor 604.

The computing system 600 may also include information storage system610, which may include, for example, a media drive 612 and a removablestorage interface 620. The media drive 612 may include a drive or othermechanism to support fixed or removable storage media, such as a harddisk drive, a floppy disk drive, a magnetic tape drive, an optical diskdrive, a CD or DVD drive (R or RW), or other removable or fixed mediadrive. Storage media 618, may include, for example, a hard disk, floppydisk, magnetic tape, optical disk, CD or DVD, or other fixed orremovable medium that is read by and written to by media drive 612. Asthese examples illustrate, the storage media 618 may include acomputer-readable storage medium having stored therein particularcomputer software or data.

In alternative embodiments, information storage system 610 may includeother similar components for allowing computer programs or otherinstructions or data to be loaded into computing system 600. Suchcomponents may include, for example, a removable storage unit 622 and aninterface 620, such as a program cartridge and cartridge interface, aremovable memory (for example, a flash memory or other removable memorymodule) and memory slot, and other removable storage units 622 andinterfaces 620 that allow software and data to be transferred from theremovable storage unit 622 to computing system 600.

Computing system 600 can also include a communications interface 624.Communications interface 624 can be used to allow software and data tobe transferred between computing system 600 and external devices.Examples of communications interface 624 can include a modem, a networkinterface (such as an Ethernet or other NIC card), a communications port(such as for example, a USB port), a PCMCIA slot and card, etc. Softwareand data transferred via communications interface 624 are in the form ofsignals which can be electronic, electromagnetic, optical or othersignals capable of being received by communications interface 624. Thesesignals are provided to communications interface 624 via a channel 628.This channel 628 may carry signals and may be implemented using awireless medium, wire or cable, fiber optics, or other communicationsmedium. Some examples of a channel include a phone line, a cellularphone link, an RF link, a network interface, a local or wide areanetwork, and other communications channels.

In this document, the terms “computer program product,”“computer-readable medium” and the like may be used generally to referto media such as, for example, memory 608, storage media 618, or storageunit 622. These and other forms of computer-readable media may store oneor more instructions for use by processor 604, to cause the processor toperform specified operations. Such instructions, generally referred toas “computer program code” (which may be grouped in the form of computerprograms or other groupings), when executed, enable the computing system600 to perform functions of embodiments of the present invention. Notethat the code may directly cause the processor to perform specifiedoperations, be compiled to do so, and/or be combined with othersoftware, hardware, and/or firmware elements (e.g., libraries forperforming standard functions) to do so.

In an embodiment where the elements are implemented using software, thesoftware may be stored in a computer-readable medium and loaded intocomputing system 600 using, for example, removable storage drive 622,drive 612 or communications interface 624. The control logic (in thisexample, software instructions or computer program code), when executedby the processor 604, causes the processor 604 to perform the functionsof the invention as described herein.

It will be appreciated that, for clarity purposes, the above descriptionhas described embodiments of the invention with reference to differentfunctional units and processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits, processors or domains may be used without detracting from theinvention. For example, functionality illustrated to be performed byseparate processors or controllers may be performed by the sameprocessor or controller. Hence, references to specific functional unitsare only to be seen as references to suitable means for providing thedescribed functionality, rather than indicative of a strict logical orphysical structure or organization.

Although the present invention has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. Rather, the scope of the present invention is limitedonly by the claims Additionally, although a feature may appear to bedescribed in connection with particular embodiments, one skilled in theart would recognize that various features of the described embodimentsmay be combined in accordance with the invention.

Furthermore, although individually listed, a plurality of means,elements or method steps may be implemented by, for example, a singleunit or processor. Additionally, although individual features may beincluded in different claims, these may possibly be advantageouslycombined, and the inclusion in different claims does not imply that acombination of features is not feasible and/or advantageous. Also, theinclusion of a feature in one category of claims does not imply alimitation to this category, but rather the feature may be equallyapplicable to other claim categories, as appropriate.

All patents, applications, published applications and other publicationsreferred to herein are incorporated by reference herein in theirentirety, including the following references:

-   [1]. 3GPP TS 23.246, “Multimedia/Broadcast Multicast Service (MBMS)    User Services; Stage 1”, Release 6-   [2]. 3GPP TS 26.346, “Multimedia/Broadcast Multicast Service (MBMS);    Protocols and codecs”, Release 6-   [3]. 3GPP TR 29.846, “Multimedia/Broadcast Multicast Service (MBMS);    CN1 procedures”, Release 6-   [4]. 3GPP TS 33.246, “Security of Multimedia Broadcast/Multicast    Service”, Release 6-   [5]. 3GPP TS 25.346, “Introduction of the Multimedia    Broadcast/Multicast Service (MBMS) in the Radio Access Network    (RAN); Stage 2”, Release 6-   [6]. Internet Group Management Protocol, IGMPv2,    http://www.ietf.org/rfc/rfc2236.txt-   [7]. “Multicast Listener Discovery (MLD) for IPv6”,    http://www.ietf.org/rfc/rfc2710.txt-   [8]. 3GPP TS 32.240, “Charging management; Charging architecture and    principles”, Release 6-   [9]. 3GPP TS 24.008, “Mobile radio interface Layer 3 specification;    Core network protocols; Stage 3”, Release 6-   [10]. 3GPP TS 29.060, “General Packet Radio Service (GPRS); GPRS    Tunnelling Protocol (GTP) across the Gn and Gp interface”, Release 6-   [11]. 3GPP TS 25.331, “Radio Resource Control (RRC); Protocol    specification”, Release 6-   [12]. 3GPP TS 23.809, “One Tunnel solution for Optimisation of    Packet Data Traffic”, Release 6-   [13]. 3GPP TR 23.837, “Feasibility study for transport and control    separation in the PS CN domain”, Release 4-   [14] 3GPP TS 23.060, “Technical Specification Group Services and    System Aspects, General Packet Radio Service (GPRS) Service    Description, Stage 2, v6.13.0, 2006-06

What is claimed is:
 1. A network device comprising: a first transmitterconfigured to transmit downlink control plane information with a firstradio access technology (RAT) of a first frequency, wherein the firstfrequency is part of a first paired spectrum; a second transmitterconfigured to transmit downlink user plane data with utilization of asecond RAT of a second frequency, wherein the second frequency is partof a second paired spectrum; wherein the downlink user plane data ismulticast multimedia data and is communicated based on the downlinkcontrol plane information; wherein the downlink control planeinformation over the first RAT and the downlink user plane data over thesecond RAT are communicated simultaneously; and wherein the first RATand the second RAT are communicatively coupled with a same gateway toallow a direct tunnel transmission from a broadcast or multicast servicecenter to a user equipment (UE).
 2. The network device of claim 1,wherein the first RAT and the second RAT utilize wideband code divisionmultiple access (W-CDMA).
 3. The network device of claim 1, wherein thedownlink control plane information comprises channel setup informationor radio access bearer setup information.
 4. The network device of claim1 further comprising: circuitry configured to handover a user equipment(UE) from the first RAT to the second RAT.
 5. The network device ofclaim 1, wherein the first paired spectrum and the second pairedspectrum are part of a same spectrum.
 6. A user equipment (UE)comprising: a receiver configured to receive downlink control planeinformation over a first radio access technology (RAT) of a firstfrequency, wherein the first frequency is part of a first pairedspectrum; the receiver further configured to receive downlink user planedata over a second RAT of a second frequency, wherein the secondfrequency is part of a second paired spectrum; wherein the downlink userplane data is multicast multimedia data and is communicated based on thedownlink control plane information; wherein the downlink control planeinformation over the first RAT and the downlink user plane data over thesecond RAT are communicated simultaneously; and wherein the first RATand the second RAT are communicatively coupled with a same gateway toallow a direct tunnel transmission from a broadcast or multicast servicecenter to the (UE).
 7. The UE of claim 6, wherein the first RAT and thesecond RAT utilize wideband code division multiple access (W-CDMA). 8.The UE of claim 6, wherein the downlink control plane informationcomprises channel setup information or radio access bearer setupinformation.
 9. The UE of claim 6 further comprising: the UE configuredto handover from the first RAT to the second RAT.
 10. The UE of claim 6,wherein the first paired spectrum and the second paired spectrum arepart of a same spectrum.
 11. A method performed by a user equipment(UE), the method comprising: receiving, by the UE, downlink controlplane information over a first radio access technology (RAT) of a firstfrequency, wherein the first frequency is part of a first pairedspectrum; receiving, by the UE, downlink user plane data over a secondRAT of a second frequency, wherein the second frequency is part of asecond paired spectrum; wherein the downlink user plane data ismulticast multimedia data and is communicated based on the downlinkcontrol plane information; wherein the downlink control planeinformation over the first RAT and the downlink user plane data over thesecond RAT are communicated simultaneously; and wherein the first RATand the second RAT are communicatively coupled with a same gateway toallow a direct tunnel transmission from a broadcast or multicast servicecenter to the (UE).
 12. The method of claim 11, wherein the first RATand the second RAT utilize wideband code division multiple access(W-CDMA).
 13. The method of claim 11, wherein the downlink control planeinformation comprises channel setup information or radio access bearersetup information.
 14. The method of claim 11 further comprising:handing over, by the UE, from the first RAT to the second RAT.
 15. Themethod of claim 11, wherein the first paired spectrum and the secondpaired spectrum are part of a same spectrum.